/*
 * CAD System for seamlessly constructing 2D and 3D scenes with aspects and motion
 * Copyright (C) 2013 Bernhard Haumacher and others
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package de.haumacher.draw5d.dataflow;

import java.util.List;

/**
 * Object that takes part in a data flow computation.
 * 
 * @author <a href="mailto:haui@haumacher.de">Bernhard Haumacher</a>
 * @version $Revision: 24 $ $Author: haumacher@googlemail.com $ $Date: 2013-08-09 17:27:26 +0000 (Fri, 09 Aug 2013) $
 */
public interface Observable extends Dependent, Markable, Validatable {

	/**
	 * Objects that must be revalidated, after this object is {@link #validate() validated}.
	 * 
	 * @see #getDependencies() The opposite direction.
	 */
	List<Observable> getUsage();
	
	/**
	 * Adds the given user to {@link #getUsage()}.
	 */
	void registerUser(Observable user);
	
	/**
	 * Removes the given user from {@link #getUsage()}.
	 */
	void unregisterUser(Observable user);

	/**
	 * Marks this instance for revalidation.
	 */
	void invalidate();

}
